Create manager

this file contains class Manager declaration.
object of the class simulates work of game tetris:
1. in constructor 7 forms are created and all of them are put into an array of Form*;
2. each (form from p.1) exists while game runs. when new form has to show up on the screen, one is randomly chosen in the array (p.1) and its parameters are set via initial values.
3. because program is a console application, user's command is asked before next move is made. it may ruin sense of the game, but this particular realization was made exclusively to train in OOD.
4. when next figure is on bottom of the screen, the field is checked and filled lines are deleted if they present.